FIG. 1 is a schematic structural diagram of an evolved network architecture in the prior art. The evolved network architecture includes a UE (user equipment), a GERAN (GSM/EDGE radio access network, where GSM refers to global system for mobile communication, and EDGE refers to enhanced data rates for GSM evolution), a UTRAN (universal terrestrial radio access network), an SGSN (serving GPRS support node), an MME (mobility management entity), an HSS (home subscriber server), an S-GW (serving gateway), a P-SW (packet data network gateway), and a PDN (packet data network).
After accessing an E-UTRAN through a radio air interface, the UE may get attached to an MME, and the MME obtains user subscription data and authentication information from an HSS server, to complete authentication on the UE. After completion of authentication, the user equipment or the MME may initiate a process of creating a bearer used to transmit user data. In this process, the MME sends a notification message to instruct the S-GW to create a bearer for the user, where the notification message carries information about an address of the P-GW and an address of an E-UTRAN network element of the user. The S-GW creates a bearer from the E-UTRAN to the P-GW for the user, where the bearer is used to transmit user data. The P-GW forwards downlink data, which comes from an external PDN, to the UE through the bearer, and forwards uplink data, which comes from the UE, to a corresponding PDN.
Also, the UE may also access a mobile network through the UTRAN/GERAN and the SGSN, and may create a GTP tunnel to the S-GW through the UTRAN/GERAN and the SGSN. The UTRAN may also create, by means of a Direct Tunnel, a GTP tunnel directly connected to the S-GW.
In an evolved network architecture, the MME only needs to process control plane signaling, and the S-GW and the P-GW are primarily responsible for forwarding user plane data. The S-GW and the P-GW may be combined into one network element, generally called a gateway. The gateway still needs to retain plenty of outbound signaling interfaces. The plenty of outbound signaling interfaces bring plenty of interface signaling. The signaling processing performance of a gateway with a dedicated hardware platform is not high and tends to become a bottleneck. To enable the gateway to process plenty of interface signaling, plenty of hardware such as universal computing processor chips needs to be added on the dedicated hardware platform. Consequently, the hardware platform of the gateway is rather complicated and too costly, which is adverse to promotion and deployment of mobile packet data networks.